Expression and localization of creatine kinase in the preimplantation embryo

Abstract

Creatine Kinase (CK) catalyses the "creatine shuttle," the reversible conversion of creatine phosphate to creatine with the liberation of ATP. This article examines the potential role of the creatine shuttle in the provision of ATP during mouse preimplantation embryo development. Using quantitative PCR, transcripts of four subunit isoforms of CK--CKM, CKB, CKMT1, and CKMT2--were detectable at all developmental stages, from the presumptive zygote to late blastocyst, but there was no obvious pattern in gene expression. By contrast, total CK biochemical activity, measured by a novel method, was relatively constant from the 2- to 8-cell stage, before exhibiting a significant decrease in activity at the blastocyst stage. Immunocytochemical studies revealed a marked association of CKB with the mitotic spindle in 2- and 4-cell mouse embryos, consistent with the proposition that the creatine shuttle plays a key role in local delivery of ATP during cytokinesis. Endogenous creatine was detected in the blastocyst at a level of 0.53 pmol/embryo. In conclusion, we believe that creatine phosphate can now be added to the list of potential sources of ATP during preimplantation development.

Metabolic compounds within the porcine uterine environment are unique to the type of conceptus present during the early stages of blastocyst elongation

“…Creatinine is the breakdown product of creatine and phosphocreatine (Salazar, ), and therefore relates to the amount of creatine being used by cellular processes (Matsuo et al, ). The interconversion of these latter two compounds by creatine kinase (CK) functions as an energy storage and release mechanism for rapid ATP generation in times of high energy demand (Forsey, Ellis, Sargent, Sturmey, & Leese, ; Yan, ). Many ATP‐related cellular processes have high energy demands, such as cell signaling, mitosis, and cell movement (Yan, ).…”

“…Additionally, rapidly dividing cells utilize glycolysis as the main source of ATP production, and CK associates with enzymes of this pathway (Yan, ). A study by Forsey et al () demonstrated the presence of CK protein and gene expression throughout mouse preimplantation embryo development, suggesting the role of the creatine‐phosphate pathway as a potential source of ATP (Forsey et al, ). The findings of these previous studies align with the temporal increase of creatine metabolism during early porcine blastocyst elongation observed in this study.…”

Metabolomic profiles of bovine cumulus cells and cumulus-oocyte-complex-conditioned medium during maturation in vitro

“…Creatine supplementation did not improve blastocyst production. This was surprising because creatine can enter the adenosine salvage pathway 40 to provide ATP for the oocytes and the enzyme creatine kinase was associated with ATP supply during spindle formation in 2- and 4-cell mouse embryos 41 . Possibly, energy storage and transportation is more established during the later stages of maturation, since the phosphocreatine concentration in cumulus cells was decreased after 23 h of maturation.…”

Measurement of ATP in Single Oocytes: Impact of Maturation and Cumulus Cells on Levels and Consumption

“…ATP consumption was significantly higher in oocytes during MI and at MII than in those arrested at GV, likely reflecting increased energy demand for processes associated with maturational progress. It has been proposed that reorganization of mitochondria towards the oocyte spindle may be necessary to provide ATP for energy consuming processes associated with spindle formation and function (Van Blerkom and Runner, ; Eichenlaub‐Ritter et al, ) and creatine kinase has recently been shown to be associated with the spindle in mouse embryos and was proposed to have a role in ATP supply for spindle formation (Forsey et al, ). These findings are in line with our observation of increased ATP consumption in MI and MII oocytes which contain a spindle when compared to oocytes at the GV stage in which no spindle is present.…”